Engine AFR Calculator
Engine AFR Calculator: Air-Fuel Ratio and Lambda
The air-fuel ratio supplied to an engine determines whether the mixture burns rich, lean, or at the stoichiometric ideal, directly affecting power, fuel economy, and emissions. This calculator computes both the raw AFR and the normalized lambda value relative to stoichiometric.
The Formula
AFR = Mass of Air / Mass of Fuel, Lambda = AFR / Stoichiometric AFR
Worked Example
An engine draws in 14.7 kg of air per kg of fuel, with a stoichiometric AFR of 14.7 (gasoline).
AFR = 14.7:1, Lambda = 14.7/14.7 = 1.0 (stoichiometric mixture)
How to Use This Calculator
- Enter the mass of air inducted.
- Enter the mass of fuel injected.
- Optionally adjust the stoichiometric AFR for your fuel (14.7 for gasoline by default).
- Click Calculate to get the AFR and lambda value.
Related Calculations
Cross-check against the Air-Fuel Ratio Calculator for general combustion AFR calculations.